X-ray apparatus



y 1950 J. T. CALDWELL 2,513,915

X-RAY APPARATUS Filed April 8, 1947 4 Sheets-Sheet 1 J T 1 DwEu.

HT'TQRNEY y 1950 J. 'r. CALDWELL 2,513,915

X-RAY APPARATUS Filed April 8, 1947 4 Sheets-Sheet 2 July 4, 1950 J. T. CALDWELL X-RAY APPARATUS 4 Sheets-Sheet :5

Filed April 8, 1947 M OK wmm I NVE NTOR Joy mm vs ZZDWELL AT RNEY Patented July 4, 1950 X-RAY APPARATUS John Thomas Caldwell, Sudbury, Wembley, England, assignor to The General Electric Company, Limited, London, England Application April 8, 1947, Serial No. 740,025 In Great Britain February 6, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires February 6, 1966 Claims.

This invention relates to X-ray apparatus and more particularly, but not exclusively, to X-ray apparatus for deep therapy.

The invention is more particularly concerned with deep therapy apparatus adapted to operate at about 220' kv. Deep therapy apparatus ar ranged to operate at this voltage at present in use may be divided into two general types. One type includes apparatus in which a shockproof tube, that is, an X-ray tube in which there is protection against electrical shock to the user, is connected by way of cables to a high tension generator. The other type includes apparatus in which a shockproof head is provided containing both an X-ray tube and a high tension transformer, the X-ray tube itself generally servin to rectify the transformer output.

Both types of apparatus suffer from certain disadvantages. Thus, in the case of the first type, the relatively inflexible high tension cables feeding the supply to the tube in its shockproof enclosure tend to impede orientation of the tube and give the apparatus an untidy appearance.

In the case of the other type, the head is necessarily somewhat heavy and bulky and tends to have a bad psychological effect on the patient receiving treatment. In addition, precise positioning with respect to the part'to be treated is difficult, necessitating, for best results, some controlled motive means such as electric drives. Additionally, since in the interests of size and Weight it is usual to energise the X-ray tube direct from the transformer, the tube is generally of the self-rectifying type. Such tubes are usual-f ly limited in output and the operating conditions are much more strenuous than when the tube is energised from a rectified supply of high tension, with consequent effect on tube life.

One object of the present invention is the provision of deep therapy apparatus in which the disadvantages set out above are minimised.

According to the present invention, in X-ray apparatus more particularly, but not exclusively; for deep therapy a, movable shockproof head is supported in a suitable manner on a pedestal or the like and the head forms a housing for an X-ray tube and. electrical equipment arranged to generate a substantial portion of the operating voltage required by th tube, the electrical equipment arranged to generate the remaining portion of the said voltage being physically separate from the head.

Thus, the operating voltage may be generated partly by a D. C. generation equipment physically separate from and external to the head and partly by high tension transformer equipment mounted within the head.

The head may be so mounted on the pedestal or the like for vertical movement up and down and the weight of the head may be substantially balanced by the weight of. the D. C. generation equipment. Both the high tension transformer equipment and the D. 0'. generation equipment may each be divided into two parts preferably equal, one part of each being associated with the cathode of the X-ray tube and the other part of each with the anode of the tube.

One form of deep therapy X-ray apparatus in accordance with the present invention and arranged to operate at a peak voltage of 220 kv. will now be described by way of example, with reference to the four figures of the accompanying drawings. In the drawings Figure 1 shows a perspective view of the pedestal and X-ray head, Figure 2 is a partly diagrammatic drawing of the X-ray head and its ancillary equipment in the pedestal, Figure 3 is a diagrammatic drawing of the electric circuit of the arrangement in'the pedestal and Figure 4 shows a view of the pedestal as in Figure 1 with part of the outside casing removed. Referring now to Figure 1 of the drawings, the apparatus comprises a pedestal l, supporting a movable shockproof head 2, and an associated control desk (not shown). The desk is arranged inknown manner withkilo-Voltage control, filament. voltage control, timing control and shutter control and is connected to the pedestal I by means of suitably insulated cables (not shown) The pedestal l which supports the shockproot head 2 also houses the D. C. generation equipment.

Referring now to Figure 2, the X-ray tube 3 is mounted in the head 2 together with two separate high tension transformers 4 and 5 each arranged to provide a peak voltage of 50 kv. on load and a filamenttransformer 2'! arranged to supply the filament of the X-ray tube 3. The head 2 which comprises a steel tank 6 with a removable lid 1 having a suitable window 8, is oil-filled and oil is continuously circulated through the head 2 by means of a pump 9 supported by the pedestal! (in Figure 1). The oil is cooled by a cooler [0 also supported by the pedestal l- (in Figure 1) and the oil is supplied to and removed from the head 2 by way of flexible tubing II and I2. The oil is actually supplied direct to the hollow anode 13 of the X-ray tube v3 in the head 2 and passes out of the anode l3 intothe head 2 so that the X-ray tube protective enclosure of lead alloy or other pro tective material of a conductive nature. This enclosure is in three parts insulated from each other. One part l6 embraces thecathode end H and neck N3 of the tube 3, another similarpart I embraces the anode end 20 and neck 2| of the tube 3 while the remaining part 22surrour1ds' the central portion 23 of the tube 3 and overlaps the other parts it and I9 so that direct radiation is cut off excepting for that which emerges from a window 24 in the central part 22. The central part 22 of the enclosure is arranged to be at earth potential while the cathode end and anode end enclosures l6 and I!) are, as will be apparent from the following description, electrically so connected to the energising apparatus as to take up a potential approximately midway between the maximum potential ofits-respective tube terminal and earth.

The end enclosures l6 and I9 connect electrically, through the partition M on which they are mounted, to two metal casings 25 and 26 of two high tension transformers 5 and 4 mounted on the other side of the partition l4. The transformer casing 25 adjacent to the cathode end I! of the X-ray tube 3 houses both a high tension transformer 5 and a tube filament transformer 21. The transformer casing 26 adjacent to the anode end 26 of the X-ray tube 3 houses only a high tension transformer 4. The leads from the various transformers 4, 5 and 2? pass to the X-ray tube electrodes I3 and 29, through the partition l4.

The supplies to the transformers 4, 5- and 21 are taken into the head by way of two high-tension cables 34 and 3| and plug and socket connections 32 and 33 on each side of the head 2; Actually, the head 2 is pivotally supported by a U-shaped bracket or gimbal 34 carried by a tubular horizontal arm 35 projecting from the pedestal (see Figure 1) and the trunnions (not shown) of the head 2 are at the sides thereof so that the pivotal axis is at right angles to the length of the X-ray tube 3'. connections 32 and33 are disposed at the trun nions and the two cables 33and 3 run up inside the tubular arm 35, one in each leg of the bracket 34, out through a suitable aperture (not shown), to the appropriate plug and socket connection 32 and 33. The U-shaped bracket 34. and tubular arm 35 are carried by a vertically moving slide 36 on the pedestal I as shown in Figure l and the bracket 34 and arm 35 can rotate through 360 about a horizontal axis at right angles to the direction of movement of the slide and can also move longitudinally of this axis. The two cables 3!) and 3| pass into the pedestal through the arm 35 and the slide 36 and there are, therefore, no trailing and unwieldy cables attached. tothe head 2.

Each high tension transformer- 4 and 5 is an auto-transformer and one end of atransformer winding isconnected to the anode |.3'or thecathode 2 90f the X-raytube 3135:1511? case may be and The plug and socket .is connected to the secondary winding 42 of a 1:1 ratio isolation transformer 43 the primary 44 of which is connected to the normal A. C. supply 45. This A. C. supply 45, through the high tension transformer 4 in the shockproof head 2, is

arrangedto generate a peak voltage of 50 kv. for the X-ray tube 3 when on load.

The conductor 31 of the high tension cable 3!! is also connected to one side of a condenser 46 of the D. C. generator 4| mounted in the casing 40. The other terminal of the condenser 45 is earthed and the condenser 46 is arranged to be charged by a high tension transformer 4'! supplied from the 250 volt A. C. supply 45. This transformer 41 comprises a primary winding 48, connected in parallel with a similar primary winding 49 supplying a similar high-tension D. C. generator 513 for the cathode end ll of the X-ray tube 3, and a secondary winding 5| connected across the condenser 46 in series with'a'valve rectifier 52, the filament transformer (not shown) of which is also mounted in the casing 45.. The D. C. generator 4| is arranged to provide a maximum of 60 kv. for the Xray tube 3 and, as will be appreciated, the D. C. generator 4| works. in series with the high-tension transformer 4 in the shockproof head 2 to provide a maximum peak of kv. on

load.

The cable arrangement 3| associated with the cathode end ll of the X-ray tube 3 is similar to that associated with the anode end 24 but, in this case, a further core conductor 53 is provided for supplying the filament 29 0f the X-ray tube 3, the filament supply using one of the main core conductors 54 as, its other supply conductor; the A. C. filament supply f2 from the control desk (not shown) is also taken through an isolation transformer 55 and this transformer is mounted in the casing 55 containingthe high-tension D. C. generator 58 associated with the cathode end H of theX-ray tube 3., A further transformer 51 for the filamentcircuit of; the X-ray tube 3 is provided in the transformer casing 25 adjacent to the cathode end ll of the X-ray tube 3 in the head 2.

Suitable means, operated from the control desk (not shown) are provided for controlling the filament current of the X-ray tube 3 and the output of both the D. C. generators 4| and 5t and the high tension transformers 4 and 5 in the shockproof, head 2, the controlof the latter can be so arranged that the peak high-tension A. C. voltage from the two transformers 4. and 5 together need never exceed the high-tension D. C. voltage from, the, two D. C, enerators 4| and 5E! and, therefore, the X-ray tube 3 need never, act as a rectifier. However underacertain conditions, a slight inverse voltage of 14). to 20 kv.. across the tube. 3: may not be. undesirable. 7

From the above description, it will be appreciated the. eacnn C. genera-tor 4!. and 5,4. delivers a maximum of 60 kv. and thehightension transformersi iaand [5 inthe-shockproofhead 2. a peak ofe50 kv. each, makinga total maximum peak voltage of 220 kv.

The three isolation transformers .43, 55 and 58, are insulated for 60 kv. D. C. between their primary and-secondary windings and the X-ray tube filamenttransformer 51 in the shockproof head 2 is provided with insulation for 50 kv. A. C. between its, primary and secondary windings. Thus, by splitting up the high tension generation equipment for the X-ray tube 3 into a part within the shockproof head 2 and a part external to the shockproof head 2 such as within the pedes-. tal l, a considerable economy in the insulation of each component is effected. Since with this arrangement it is possible to maintain the spacings between the tube electrodes I 3 and 29 and the tube shields I6, I9 and 20 and between the tube shields I6, l9 and 22 and the tank walls 1 of the head 2 at relatively small values.v It also assists in reducing the space-occupied by the X-ray tube, that is to say, the size of the head 2.

The two D. C. generator casings 40 and 56 are enclosed within the pedestal l by removable side covers 69 and '10 (Figure 1) and are arranged similarly as herein described, one on each side of the guideway 59. In Figure 4 one side of the pedestal I is partly removed to show one of the D. C. generator'casings 40 in position, the other D. 0. generator casing 56 being hidden by the side cover 10. Referring now to Figure 4 in conjunction with Figure 2, the vertically moving slide 36 on the pedestal l, which slide carries the head 2, runs in suitable guideways 59 and two supporting cables 60 and 6| run from each side of the slide 56 vertically upwards to two pulleys 62 and 63 mounted one on each side of the path of movement of the slide 36. Each cable 60 or 6| passes over its pulley, 62 or 63 then downwards and under a pulley 64 or 65 fixed to one of the casings 40 or 56 containing the higher tension D. 0. generator 4| or 50, and up again to a cable anchor 66 or 6! on a bracket 68 on the pedestal I. Thus, there is one D. 0. generator casing 40 or 56 hanging on each side of the path of movement of the slide 36 and each generator casing 40 or 56 is free to move up and down in the pedestal I. The weight of each D. C. generator casing 40 or 56 and the equipments therein is arranged to be equal to the total weight. of the slide 36 and the parts supported thereby and it will be appreciated that the weight of the D. C. generator casings 40 and 56 balances the weight of the slide 36 and its supported parts and that when the slide 36 moves, the casings 40 and 56 each move only half the distance the slide 36 moves. Naturally, the high tension cable 30 or 3| running from each D. C. generator 4| or 50 to the shockproof head 2 is so arranged in the pedestal i that the slide 36 is free to move up and down and the head 2 may rotate about and move longitudinally of the axis of the tubular arm 35 and U-shaped bracket or gimbal 34 supporting the shockproof head 2.

As the two D. C. generator casings 40 and 56 are so arranged that their range of movement is from the bottom of the pedestal l to about halfway up, a clear space is left at the top on each side of the path of movement of the slide 36 and these two spaces are occupied by the motor H, pump 9 and cooler I of the oil cooling system, the motor H and pump 9 on one side and the cooler ID on the other.

By arranging that the D. C. generator casings 40 and 56, and the equipments therein balance the weight of the shockproof head 2, the necessity of providing special balance weights is done away with and the total weight of the equipment thereby'reduced. Further, it will be appreciated that,bydividing the high tension generation equipment into two parts, part in the pedestal I and part in the shockproof head 2, the

disadvantages of known deep therapy apparatus,

referred to in the opening paragraphs of the specification, are avoided. Thus, since only a part of the total operating voltage is-generated external to the shockproof head 2, high tension cables 30 and 3! may be used which arelighter than those used in the case where the total operating voltage is generated external to the head 2.- The use of lighter cables 30 and3l allows the adoption of the arrangement described above in which the cables run through the supporting means of the head 2. Obviously, the head 2 is considerably smaller and lighter in weight than those known constructions in which thehead carries all the high tension generation equipment.

I claim:

1. A high voltage deep therapy X-ray apparatus operable froma normal low voltage alternating current sourceof electric energy in the order of 250 volts, for example, said apparatus comprising a shock-proof head, an X-ray tube operable at a highvoltage of the orderof 220 kv., means to mount said tube in said head, means to shiitably support said head, electrical equipment located within said head and operable from the low voltage alternating current, source of electric energy for generating a substantial portion of the high operating voltage required by said tube, electrical equipment located external to and physically separate from said head and operable from the low voltage alternating current source of electric energy for generating the remaining portion of the operating voltage vfor said tube, said equipments being series-connected whereby to add the voltages generated thereby, and means to supply said low voltage alternating current source of electrical energy to both said equipments. 7

2. An X-ray apparatus according to claim 1, wherein both said equipments are divided into two parts whereof one part of each said equipments is associated with the cathode of the X-ray tube and the other part of each said equpments is associated with the anode of the X-ray tube so that the cathode of the tube is supplied with voltage from two series-connected parts each of which is from a different equipment and the anode of the tube is supplied with voltage from two series-connected parts each of which is from a different equipment.

3. An X-ray apparatus according to claim 1 wherein a housing is provided for the secondnamed equipment, wherein said housing is mounted for free vertical movement and wherein means is included to counterbalance said housing against the head. v I

4. A high voltage deep therapy X-ray apparatus operable from a normal low voltage alternating current source of electric energy in the order of 250 volts for example, said apparatus comprising a shock-proof head, an X-ray tube operable at a high voltage of the order of 220 kv., means to mount said tube in said head, means to shiftably support said head, high tension transformer equipment located within said head and operable from the low voltage alternating current source of electric energy for generating a substantial portion of the high operating voltage required by said tube, direct current generation equipment located external to and physically 7" Separated from said head and operable from the low voltage alternating current source of electric energy for generating the remaining portion of the operating voltage for said tube, said equipments being series-connected whereby to add the voltages generated thereby and means to supply said low voltage alternating current source anode of the tube is supplied with voltage from two series-connected parts each of which is from a different equipment.

6. An X-ray apparatus according to claim 4 wherein a housing is provided for the secondnamed equipment, wherein said housing is mounted for free vertical movement and wherein means isincluded to counterbalance said housing against the head.

7. A high voltage deep therapy X-ray apparatus operable from a normal low voltage alternating' current source of electric energy in the order of 250 vo1ts,for example, said apparatus comprising a shock-proof head, an X-ray tube operable at a high voltage of the order of 220 kv.,

means to mount said tube in said head, means. to shiftably support said head, high tension transformer equipment located within said head .2."

and operable from the low voltage alternating current source of electric energy for generating as an alternating voltage a substantial portion of the high operating voltage required by said tube, direct current generation equipment located external'to and physically separate from said head and operable from the low voltage alternating current source of electric energy for generating the remaining portion of the operating voltage for said tube, said equipments being series-connected whereby to add the voltages generated thereby and means to supply said low voltag alternating current source of electrical energy to both said equipments.

8. An X-ray apparatus according to claim 7 wherein both said equipments are divided into two parts whereof one part of each said equipments is associated with the cathode of the X-ray tube and the other partof each said equipments is associated with the anode of the X-ray tube so that the cathode of the tub is supplied with voltage from two series-connected parts each of which is from a different equipment and the anode of the tube is supplied with voltage from two series-connected parts each of which is from a different equipment.

9; A high voltage deep therapy X-ray apparatus operable from a normal low voltage alternating current source of electric energy in the order of 250 volts, for example, said apparatus comprising a shock-proof head, an X-ray tube operable at a high voltage of the order of 220 kv., means to mount said tube in said head, means to shiftably support said head, high tension transformer equipment located within said head for generating as an alternating voltage a substantial portion of the high operating voltage required by said tube, and direct current generation equipment located external to and physically separate from saidhead for generating the remaining portion of the operating voltage. for said tube, said equipments being series-connected whereby to add. the voltages generated thereby, both said equipments being divided into two parts whereof one part of each said equipments is associated with the cathode of the X-ray tube and the other part of each said equipments is associated with the anode of the X-ray tube so that the cathode of the tube is supplied with voltage from two series-connected parts each of which is from a different equipment and the anode of the tubes is supplied with voltag from two series-connected parts each of which is from a different equipment.

10. A high voltage deep therapy X-ray apparatus operable from a normal lowvoltage alternating current source of electric energy in the order of 250 volts, for example, said apparatus comprising a. shock-proof head, an X-ray tube operable at a high voltage of the order of 220 km, means to mount said tube in said head, means to shiftably support said head, high tension transformer equipment located within said head for generating as an alternating voltage a substantial portion of the high operating voltage required by said tube, direct current generation equipment located external to and physically separate from said head for generating the remaining portion of the operating voltage for said tube, said equipments being series-connected whereby to add the voltagesgenerated thereby, a housing for the secend-named equipment, means to mount said housing for free vertical movement, and means counter-balancing said housing against the head.

JOHN THOMAS CALDWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date D. 100,945 Graves Aug. 25, 1930 1,775,853 Goldfield Sept. 16, 1930 2,216,210 Mutscheller' Oct, 1, 1940 2,232,014 Simon Feb. 18, 1941 

